This invention relates to a tension controlling device for tensioning roving before it is wound into a package.
Generally today roving is tensioned by passing it over and under a series of parallel tensioning or spreader bars. The bars are fixedly held in relationship to each other. These bars impart tension in the roving as it travels to the winder. Tension is varied by adding or subtracting bars.
But the tension in the roving is not controlled.
While a package is being wound the tension in the roving will vary up and/or down. Also, the tension can vary from package to package. All of the sources of this varying tension are not known. But it is known that the bars change temperature and that the bars collect binder, dirt and fuzz on their surfaces during the winding of packages. These changes will alter the coefficient of friction of the bar surfaces resulting in a change in roving tension. Also, strand supply packages can vary in binder content and in how tightly they are wound. So the amount of pull needed to remove strand from the package can vary from strand package to strand package or even within a single strand package resulting in varied strand and roving tension.
Roving packages which are wound with varying tension are a problem. The package will have a varying density. Areas of high density will result when the tension is high, and areas of low density will result when the tension is low.
A roving package made with varying tension may not have flat ends. Rather it can have high and low areas on its ends. Nonuniform package ends can result in poor package run-out of the strand because the strand can become tangled.
If a package is wound with a high tension on the roving when winding the outside of the package, the center portion of the package may be crushed or the center portion of the package can pop (telescope) out. Also, a package with a high density outside is likely to collapse during run-out of the roving during use of the package. This would cause the remaining portion of the package to be scrapped.
An area of the package wound with a low tension on the roving can also be a problem. That area of the package may collapse resulting in a ruined package. A low tension area can slough off and tangle during package use when the roving is being pulled out. This would cause the remaining portion of the package to be scrapped.
These areas have all been problems with the current 30-50 pound roving packages.
But these problems become even more critical when making large roving packages. Today many roving packages that weigh 350-500 pounds are being wound and sold. It can readily be seen that ruining one of these large packages or collapsing one of these large packages before full run-out (by the user) would be a serious problem.
Clearly better tension control is needed today in the winding of roving packages.